Resolving dependencies...
cabal: Could not resolve dependencies:
trying: base-4.9.0.0/installed-4.9... (dependency of happstack-ixset-0.5.0)
next goal: happstack-util (dependency of happstack-ixset-0.5.0)
rejecting: happstack-util-6.0.3, happstack-util-6.0.2, happstack-util-6.0.0
(conflict: happstack-ixset => happstack-util>=0.5 && <0.6)
rejecting: happstack-util-0.5.0.3 (conflict: mtl==2.2.1, happstack-util =>
mtl>=1.1 && <2.1)
trying: happstack-util-0.5.0.2
next goal: strict-concurrency (dependency of happstack-util-0.5.0.2)
rejecting: strict-concurrency-0.2.4.1, strict-concurrency-0.2.4 (conflict:
base==4.9.0.0/installed-4.9..., strict-concurrency => base>=4 && <4.6)
rejecting: strict-concurrency-0.2.3 (conflict: base==4.9.0.0/installed-4.9...,
strict-concurrency => base>=3 && <4.3)
rejecting: strict-concurrency-0.2.2, strict-concurrency-0.2.1 (conflict:
base==4.9.0.0/installed-4.9..., strict-concurrency => base>=3 && <4)
rejecting: strict-concurrency-0.2, strict-concurrency-0.1 (conflict:
base==4.9.0.0/installed-4.9..., strict-concurrency => base<4.3)
Dependency tree exhaustively searched.